Is it practical to attempt to build a 3D hologram generator that is full color and big enough to recreate a watermelon full size? If so, is real-time control feasible?
closed as off topic by David Z♦ Mar 27 '13 at 16:35
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Based on my one day lab practice experience, I will cover the general part of your question.
Color of hologram
Compared to a conventional photo a hologram additionaly saves phase (of light wave) information. Depending on the viewport the wave reconstruction allows the observer the experience color 3D pictures. However this reconstruction has a flaw: the color changes like a rainbow (color hologram on wiki) as can be seen in holograms on a credit card. Holograms demand the same wavelength for reconstruction than creation. I do not know whether there is a procedure to capture real color holograms using 3 capturing wavelengths, better than the above shown mice from wiki.
Cost of elements for a holographic recorder
Cost of elements for a hologram recorder: Using laser of long coherence length(depth of focus), stable mechanics and environment, beam splitter, beam expander, a photobox full o sand and holographic recording media, this is easiliy done below 30k dollar. Scale this up from my $5\cdot5\,$cm$^2$ using stronger beam expander. Your answer is yes but the question of the quality of the hologram remains. A proof is the initial linked picuture of a mice, that is small compared to a water melon.